The blue chip, a unit of state-owned China Merchants Group, said it aims to control costs in the second half partly by managing investment spending and the pace of development of key projects.
Net profit for the six months ended June 30 fell to US$223 million from $260.62 million.
China Merchants is the largest container terminal operator by volume in Shenzhen, mainland China's second-biggest port by volume after Shanghai. It controls nearly all the terminals in the western part of Shenzhen's port, including the Shekou, Chiwan and Mawan container terminals.
It also has stakes in ports in Shanghai, Hong Kong, Tianjin, Qingdao, Ningbo and Zhangzhou.
China Merchants' core ports business contributed earnings before interest and tax of $229.65 million in the first half, down 28 percent from a year earlier, accounting for 80 percent of the company's total EBIT.
China Merchants attributed the fall in earnings to a decline in China trade, resulting in weaker demand for container port services.
During the period, China Merchants' container throughput fell 19 percent to 20.35 million TEUs. Throughput at its Shenzhen ports totalled 4.23 million TEUs, down 28 percent from the first half of 2008.
Apart from its core container business, China Merchants has been increasing its investment in terminals with bulk cargo operations. The company's bulk cargo throughput fell 5.2 percent in the first half to 108 million metric tonnes.
China Merchants has also been seeking overseas investment opportunities. The company formed a $60 million joint venture with Vietnam National Shipping Lines Corp in September last year to build and operate the Ben Dinh Sao Mai Deep Seaport in Ba Ria-Vung Tau province, Vietnam. The company owns a 49 percent stake in the venture.
China Merchants will invest around $1 billion to develop six container berths at the port in southeastern Vietnam, and said it projects the venture will start contributing to earnings about two years from the start of construction.